Method of and apparatus for drying materials



May 5, ,1925.

J. J.' MERRILL METHOD OF AND APPARATUS FOR DRYlNG MATERIALS Filed Aprii 18. 1924 2 sheets-sheet 1 gai NNUU...

lllillllllllllllllllllllIllllllllllllllllllli J. J. MERRILL METHOD 0F AND APPARATUS FOR DRYING MATERALS May 5, 1925.

Filed dApril 1s. 1924 2 sheets-sheet a IIIIIIIIUM III VIl|IllllIllllilllllllllllllllIllllll Patented May 5,` 1925.

UNITED Isriviss PATENTOFFICE.

JOSEPH J'. MERRILL, 0F CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 INTERNATIONAL PATENTS DEVELOPMENT COMPANY, A CORPORATION OF DELA- .WARE

`METHOD OF AND APPARATUS FOR DRYING MATERIALS. l i

Application tiled April 18, 1924. Serial No. 707,397'.

T0 all whom t may concern:

Be 1t known that I, Josnrn J. MERRILL, a

citizen of the United States, residing at Chi? cago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in the Method of and Apparatus for Drying Materials, of which the following is a specification. l

My invention relates to certain improvements in dryingmaterials of a granular or pulverulent character, and the principal object of the invention is to provide a method of and 'apparatus for drying materials of this character which can be operated at a minimum fuel and labor cost and which will effect the saving of all of the dried material even when some of itis in a' very finely divided state. t l

The invention is concerned particularly with lthe problem of drying crystalline dextrose (although it is equally well adapted to other materials of like character) which operation is attended with some difficulties. The sugar, obviously, cannot be submitted to too high a temperature because of its tendency to melt. lVhen dried it contains alarge. amount ofvery fine dust which might be clescribed as an impalpable powder. This'dust is extremely hard to collect in any ordinary dust collector, and if it be allowed to escape from thea )paratus it will float for long dis-- tanees in t 1e air and create a nuisance. The water content of the dust laden air issuing from the drying apparatus mustbe relatively low otherwise condensation will take place in the dust collectors causing them to become clogged.

Having these considerations in view, my invention has sought to provide and has been successfulin providing a drying apparatus and a method of drying whereby a material such as crystalline dextrose may be dried Aefficiently `and to the extent required, Without appreciable loss of material from the apparatus,` and at'a'minimum cost in fuel and labor.

The y'invention is illustrated in a preferred embodiment, in the accompanying drawings, wherein Fig. 1 is a View in side elevation, with certain parts in section, of a drying apparatus constructed in accordance with my invention.

Fig. 2 is a plan view of the first or upper drier, and

n Fig. 3 is a similar view, with parts in seetlon, of the second or lower drier.

The material to be dried is introduced through chute 10, for example, into the upper end of a rotary inclined drying drum A, which has been termed the first drier, and passes from the lower end of drying drum A through pipe 11 and chute 12 into the upper end of inclined rotary drying drum B, termed the second drier. From the lower end of this drier the material passes to a screw conveyor C. The air (or drying gas, air bein# used preferably) for accomphsh ing the drying operation is heated by heater D and passes through the second drum B in the same direction as the material moves, the air circulation being brought about by a fan or blower E, and is then sent through a dust collector, preferably a cyclone collector F. 1n which it is ridded of a large part -of the solids in suspension. yFrom dust collector F 'the airpasses through a conduit 13 to the lower end of the first drum A, the air being consequently forced through the first or upper. drum A in the direction counter to the movement of material through this drum. From drum A the air passes through conduit 14 into a second dust collector @preferably of' a different type from dust collector F.

The. material passes through the drums A and B by gravity, the interior of the drums being preferably provided with any means common to drum driers' for stirring or turning the material over, so that it is exposed to the currents of heated air passing through thev drums.` At the upper and lower ends of drum A are header chambers 15 and 16. The lower drum B is similarly provided with a header chamber 17 at its upper end and a chamber casing 18 at its lower end. The heater D consists preferably of a steam coil 19 fr exhaust steam and a steam coil 20 for live steam located ina box 21, the upper end 22 of which is open to the atmosphere while the other end communicates with the header casing 17 of the lower drum which may be provided with a damper 23.

Conveyor C is arranged under the header casing 18 at the lower end of drum B, the bottom lof which casing opens into the conveyor. A pipe 24 leads from header casing 18 to blower E and a pipe 25 from thepump to the cyclone collector F, the spout 26 of which discharges solids into conveyor C.

27 is a pipe leading from dust collector F to the air conduit 13. The latter has a branch 2S leading through header casing 16 into the lower end of drum A. Pipe 14 leads from the top of header casing 15 to dust collector G which consists of a vessel having a perforated steam ring 29 located in its upper end. The steam knocks down whatever dust there may be in the air entering vessel G. The condensate and solids pass oft' throng a pipe 30 at the bottom of vessel G.

It will be' observed that the air heated by heater D moves through drum .B in the same direction that the partially dried inaterial moves. The air passing through this drum is hotter than the air passing through drum A but as air and material move in the same direction the heating e'ect of the air on the material is less than 'it would be if -the air were passed in one direction through the drum and the material in the opposite direction, as is the case in drum A since each particle of lsolid matter will come into contact with a greater amount 'of air in the latter case than in the former. Consequently the tempera-ture of the air enteringr the apparatus may be relatively high, which makes ior economy of operation. The material in' drum B isrelatively dry, a considerable portion of its moisture having been removed in drum A. Consequently the moisture content of the air issuing from drum B will be relatively. low and as its temperature is fairly high, it -is possible to use an ordinary cyclone dust collector (the dust collector F) to remove the bulk of the solids from the air before the air is passed on to drum A. This is another item of economyr as a cyclone dust collector is cheap in construction and, within certain limits, eflicient and economical to operate. Moreover, the solids collected by the 'cyclone dust collector F are in a dry state. However, it is not practical, by means of a cyclone dust collector, to rid airhof the very `tine dust or iinpalpable powder *found in considerable quantities in the crystalline dextrose which this apparatus is particularly designed to handle. The air passing through pipes 27, 13, 28 will contain a considerable amount of such line solids but in entering drum A it is blown against the body of relatively' damp, fresh sugar introduced into drum A through chute k10. flhis materia-l is turned over and thrown into the air by the rotation of the drum and serves as a means for collecting the line, dry particles entering the lower end of the drum .with the drying medium. In this drum, as has been stated, the material moves in one` direction and the air in the opposite direction so that a larger volume of air is brought in to contact with the material than i's the case in drum B, facilitatingthe process of knocking down the line, dry particles just referred to. This is vfeasible because the material is relatively damp and the tempera-i ture of the air considerably'lower than the temperature at which it entered the second drum B. `The air issues from drum A at quite a low temperature. `In other words, the heat of the air is used to its fullest extent; This outflowing air current may carry with it some solids but as its moisture content will be relatively high it is not desirable Ato use a cyclone collector at this point. Instead, wliat solids there may be in the air (the quantity will not be great in view of the dust collecting actionl which takes place in the drum A) are knocked down by the steam issuing from steam ring 29. The dilute sugar liquor thus formed may be used in the process of manufacturing dextroseso' that there is no ultimate loss.

yhen this material is dried iii a single drum with the material passing in one direction and the air inthe opposite direction, it was found impossible to prevent the escape to the atmosphereof quite a large amount of finely divided solidsr which were consequently Wasted and, moreover, floated through the air and settled at long distances from the plant. Furthermore, the dried material collected in considerable quantities in the header chamber at the upper end of the drum and had to be slioveled out intermittently at, the cost of somed labor. The iinproved method o drying the material over comes these objections entirely. No appreciable amount of dry material escapes from the apparatus. The operation is entirely automatic and the quantity of steam used in the steam coils, in proportion to the amount of material dried, is lessened. The drying is also accomplished more uniformly and effectively. 4 l

Realizing that modications might be made vin the construction of the apparatus invention, I desire to make it clear that it is my intention to'claim all modifications within the scope of the appended claims.

' I claim:

1. In drying apparatus, the combination of two driers, means for causing the material t-o pass through said driers in succession, means for causing theheated air to pass initially through thel second of said driers andthen through the first drier, and a cyclone dust collector through which the air passes 'from the second drierto the first drier.v4 v

2L In drying apparatus, the combination of two driers,means for causing the material to pass through said driers in succession, and means for causing heated air to pass initially through the second of said driers in the saine direction as the movement of the material therethrough, andl then through the first drier.

3. In drying apparatus, the combination without departure from the principles of my Lesage-oe` of two driers, means for causing the ma- `pass initially through the second of said driers in the same direction as the movement of the material therethrough, and then through the first drier in a direction opposite to the direction of material passing through said first drier.

4. In drying apparatus, the combination of two driers, means for causing the ma.- terial to pass through said driers in succession, mea-ns for causing heated air to pass initially through the second of saidv driers in the same direction as the movement of the material therethrough and then through the first drier ina direction opposite to the direction of material passing through said first drier, 'and' a dust collector through which the air passes from the second drier to the first drier.

5. In drying apparatus,l the combination of two driers, means for causing the ma` terial to pass through said driers in succession, means 'for causing the heated air to pass initially through the second of said i driers and then through the first drier, and

a dust collector into which the air issuingy from the first vdrier is introduced.

j 6. In drying apparatus, the combination of two driers, means for causing the material to pass through said driers in succes-V sion, means for causing the heatedair to pass initially through the second of said driers and then fthroughthe first drier, a dust collector into which the air issuing from the first drier is introduced comprising a Vessel, and means for injecting steam intol the vessel.

7. In drying apparatus, the combination of two driers, means for causing the material to pass through said'driers in succession, means for causing the heated air topass initially throughv the second of said driers and then through the first drier, a

dustcollector to remove the dust fromthe air while passing from the second to lthe first drier, and a dust collector into which the air'issuing from the first drier is introduced. i

.8. In a drying apparatus, the-combination of two driers, means for causingthe material to pass through said driers in succession, means for causing heated air to pass initially through the second of said driers in the same directionv as the movement of the material therethrough, and then through the first drier in a directionv opposite to the direction of material passing through said first drier, a cyclone dust collector through which the. air passesfrom the second drier to the first drier, and a dust collector .into which the air` from the first .drier is introduced comprising a vessel and means for in- -jecting steam into said Vessel'.

9. dryin apparatus, the combinationl of an mcline rotary drying drum, means lfor feeding material into the upper end of A initially through the second drum from the upper end to the lower end thereof, and then into and through the first drum. A

10'. In drying apparatus, the combination of an inclined rotary drying drum, means for feeding material into the upper end of the drum, a second inclined rotary drying drum, means for introducing material which has passed through the first drum into the upper end of the second drum, and means for heating lthe air and causing it to pass initially through the second drum from the upper end to the lower end thereof, and then into andV through the first drum from the lower end to the upper end thereof.

11. In drying apparatus, the combination of an inclinedrotary drying drum, means for feeding material' into the upper end of the drum, a second inclined rotary drying drum, means for introducing materlal which has passed throughl the first drum into the `upper end of the second drum, means for heating the air and causing it to pass initially through the second drum and then into .heating the air and causing it'to pass. initially through the seconddrum from the upper en d to the lower end thereof and `then into and through the first drum from the lower end to the upper endvthereof, and a dust collector through which the air passes from the second drum to the rst drum.

13. In drying apparatus, the combination of an inclined rotary drying drum, means for feeding material into the. upper end of the drum, a secondv inclined rotary drying drum, means for introducing material which has passed through the first drum into the uppervend of the second drum, means for heating the air and causing it to pass initially through the second drum from .the upperend to -thelower end thereof and then into'and through the first drum from the lower end to the upper end thereof, a dust collector through which the air passes from the second drum tojthe first drum, and a air `into the upper header of the seconddrum, a conveyor for removing dried material from the header chamber at the lower end of the second drum, a cyclone dust collector which receives air and suspended particles from the header chamber at the* lower end of the second drum and discharges solids into said conveyor, a conduit' leading from the cyclone dust collector to the header chamber at the lower end of the first drum, means for introducing material into the upper end of the rst drum, means for introducing material taken fromA the lower end of the first drum into the upper end of the second drum, and means for producing a circulation of heated air through said drums and dust collector.

15. In drying apparatus, the combination of a rotary, inclined, drying drum having header chambers at opposite ends thereof, a second inclined rotary drying drum having header chalnbers atits upper and lower end, an air heater for introducing heated air into the upper header of the second drum, a conveyor for removing dried material from the header chamber at thel lowerrend of the second drum, a cyclone dust collector which `receives air and suspended particles from the header chamber at the lower end of the second drum and discharges solids into said conveyor, aiconduit leading from the cyclone dust collector to the header chamber at the lower end of the first drum, means for introducing material into the upper end of the first drum, means for introducing material takenfrom the lower end of the. first drum into the upper end of the second drum, means for producing a circulation of heated air through said drums and dust collector, and a dust collector connected with the header chamber at thc upper end of the first drum.

16. Method of drying granular or pulverulent material which comprises causing the material in a state of dispersion to be moved successively through two drying spaces, introducing a body of drying gas into the second of said drying spaces and causing it move therethrough and then into and through the first of said spaces, and removing suspended particles from the drying gas as itpasses from one of said drying spaces to the other.

17. Method of drying granular or pulverulent material which comprises causing the material in a state of dispersion to be moved successively through two drying spaces and introducing a body of drying gas into the secondl of said drying spaces and causing it to move therethrou h in the same direction as the movement o the material therethrough, and then causing it to enter and move through the other drying space.

18. Method of drying granular or pulverulent material which comprises causing the material in a state of dispersion to be moved successively through two drying spaces and introducing a body of' drying gas into the second of said drying spaces and causing it to move therethrough in the same direction as the movement of the material therethrough, and then causing it to enter and move through the other drying space `in -the direction opposite to the movement of the material through that space.

,19. Method of drying granular or pulverulent material which'comprises causing the material in a state of dispersion to be moved successively through two drying spaces, introducing a body of drying gas into the second of' said-drying spaces and causing it to move therethrough in the same direction as the movement of the material therethrough, then causing it to enter and move through the other drying space in the direction opposite to the movementof the material through that space, and separating suspended particles from the airxy as it passes from one of said spaces to the other.

" JOSEPH J. MERMLL. 

